test-inmem-listener.go

type InMemListener struct {
	connCh chan net.Conn
}

func newInMemListener() *InMemListener {
	return &InMemListener{
		connCh: make(chan net.Conn, 1),
	}
}

func (i InMemListener) Accept() (net.Conn, error) {
	return <-i.connCh, nil
}

func (i InMemListener) Close() error { return nil }

func (i InMemListener) Addr() net.Addr {
	return &net.UnixAddr{
		Name: "InMemListener",
		Net:  "memory",
	}
}

func TestHttpServerInMemory(t *testing.T) {
	mux := http.NewServeMux()
	mux.HandleFunc("/test", func(w http.ResponseWriter, r *http.Request) {
		w.Write([]byte("OK"))
	})

	srv := httptest.NewUnstartedServer(mux)

	ln := newInMemListener()
	conn1, conn2 := net.Pipe()
	ln.connCh <- conn2
	srv.Listener = ln
	srv.Start()
	c := http.Client{
		Transport: &http.Transport{
			DialContext: func(ctx context.Context, network, addr string) (net.Conn, error) {
				return conn1, nil
			},
		},
	}
	resp, _ := c.Get("http://localhost/test")
	respBody, _ := io.ReadAll(resp.Body)
	assert.Equal(t, string(respBody), "OK")
}